Pipe joint



G. M. EATON ET AL PIPE JOINT sept. 19, 1933.

Filed Dec. 23, 1931 2 Sheets-Sheet l INVENTORS .mw LN M /l/ M @aA/5MM.

Sept. 19, 1933. G. M. EATON ET A1.

Filed Deo 23, 1951 2 Sheets-Sheet 2 .l .2 mm ..2 ..2 ..2 w wn@ Patented Sept. 19, 1933 UNITED STATESI PATENT OFFICE PIPE Jonv'r George M. Eaton, Ben Avon, and Howard J. Burnsh, Sewickley, Pa., assignors to Spang,

Chalfant & Co., Inc.,

Pittsburgh, Pa., a corporation of Pennsylvania Application December 23, 1931 Serial No. 582,822

5 Claims. (Cl. 285-146) 5 tubing for oil wells.

The construction which we have developed is designed to overcome such characteristic dimculties as are incurred inthe use of pipe or casing in oil wells, namely, the parting of a string of pipe or casing at a joint due to insufficient strength, leakage of pressure fluid through the joint resulting in the cuttingor 'washing away of the pipe wall, and the galling of threads due to damage caused to the threads when stabbing, which is the initial operation in the making up of a threaded connection when running a string of pipe in a well.

It is one object of this invention to provide means for joining together the consecutive lengths of pipe in a substantial manner so as to obtain maximum strength at the joint without increasing the wall thickness or with a minimum increase thereof of that portion of the pipe in which 'the screw threads are cut.

Another object of Aour invention is the provision of a thread form that permits stabbing without damage to the thread, contour or the lateral faces of the thread form, thereby minimizing the destructive galling of the threads.-

Another object is to provide a thread with lateral contact surfaces, the depth of which are gradually reduced from a maximum at azone of greatest depth intermediate of its length tol a vanishing point at each end of the thread, thereby increasing the strength of the threaded connection.

Another object is to provide means for effecting a substantial seal at the joint to prevent leakage of pressure fluid therethrough'.

Another object is to provide an intermediate annular sealing surface between the adjacent or tandem threads to insure maximum metal backing at the seal to resist radial stresses and also serve as a fulcrurn or central bearing point around which the overlapping intermeshing threaded ends of adjacent pipe elements may rock when the joint is subjected to exure or bending stresses. The functioning of this feature will insure the maintaining of an effective hydraulic seal.

Another object is the provision of a seal between the overlapped threaded ends of pipe elements in such a position that the stresses due to the wedging effect at the seal are at a minimum thereby reducing the tendency of corrosion, which condition is accentuated in metal under stress. Referring vto the accompanying drawings, Fig. 1 is a longitudinal section of one form of our invention, the view having been taken on a plane 50 which includes the axial centers of the two pipes connected by our improved threads, the pipes so connected being broken away shortly beyond the ends of the -joint and also being broken away longitudinally a short distance radially from the interior walls of the pipes and the joint being shown as it appears when the threads of the ypipes arev completely engaged.

. Fig. 2 shows a section like that in Fig. 1 except that lthe complementary threaded portions on the two pipes are shown in their relative positions at the close vof a stabbing operation preparatory to screwing together these threaded portions.

Fig. 3 is a section like that in Fig. 1 except 75 lthat in Fig. 2 the threads have lateral clear ances with straight seals at their ends while in Fig. 1 the ,threads have clearances atv their crests and roots. with tapered seals at their lateral faces.

Fig. 4 shows a section of the same character as Fig. 1, each pipe having a plurality of threaded portions separated by tapered sealing surfaces,'whereas in Fig.' 1 the sealing is effected by tapered surfaces at the ends of the threaded portions.

Fig. 5 is a section of the same character as Fig. 2 showing the pipes of Fig. 4 in their stabbing relation.

Referring first to Figs. 1 and 2, 10 and 11 90 represent two pipes with the end 12 of the former Within the end 13 of the latter. The exterior wall of the pipe-end 12 is providedin Fig. 1 with a thread 18 mating with a thread 19 on the interior wall of the pipe-end 13. Preferably,

only the intermediate portions of the pipe-ends Y 12 and 13 are threaded, the external unthreaded portions 14 and l5 which extend along the pipeend 12 longitudinally of the pipes in opposite directions forming annular preferably tapered sealing surfaces with `the internal unthreaded portions 16 and 17 respectively which are on the pipe-end 13 beyond the opposite ends of the threaded portion thereon.

The depth of the turns of the threads 18 and 19 are gradually reduced in both directions from a maximum at the zone of greatest depth midway of the length of the threaded portions to the vanishing vpoints 20. at the ends of the threaded portions.

Y The successive crests of the turns of the thread" Fig. 3 is substantially like Fig; 1 except that in 18 cn the pipe-end 12 extend outwardly radially tFig. 3 the angles which the opposite sides of from the axis of the pipe lil` a slightly greater distance as the crests are viewed successivelyv from the thinner portions of the pipe-end 12 toward the thicker portionsthereof. vThe successive crests of the turns of the thread 19 on the pipe-end 13 extend inwardly radially toward the axis of the pipe 11 a slightly greater distance as the crests are viewed successively from the thinner portions of the pipe-end 13 toward the thicker portions thereof. The distances of the successive crests from the axes of the pipes 10 and 11 are such thatA the crests on the two threads will not interengage until the pipe-ends have been telescoped during the stabbing operation. At the close of the stabbing operation the advancing lcorners of some of the turns on one pipe-end will abut 1against the corresponding corners of the turns of the'other pipe-end, as shown along the intermediate portions of Fig. 2. In this view the turns of the threads on each pipe-end Aare positioned ready to move spirally between the turns of the other pipe-end, whereby the turns on each pipe-end sink deeper and deeper into the spiral spaces between the turns of the other pipe-end until finally the pipes* 10 and 11 have been drawn together so that the sides of the turns on cach pipe-end are engaged tightly with the sides of the turns on the other pipe-end.A In Fig. 1 there are clearances 21 between the crests of the turns of each pipe-end and the root on the other pipe-end. In Fig. 2 the unthreaded portions 14 and 15 on the pipeend 12 form a seal with the unthreaded portions 16 and 17 on the pipe-end 13 when the joint is screwed up tightly. Preferably these Unthreaded portions are slightly tapered so'as to increase thetightness of the seals as the pipes arescrewed together.

Looking atthe pipe-end 11 and particularly at. Fig. 2 where the pipe-ends 11 and 12 are shown' mostly separated, it is seen that the roots of the thread become successively shallower from an intermediate portion to theA outer end of the pipe-end v11; that the crests of the thread from the 'said portion to the inner end of the threaded portion become successively shorter; that the crests of the threads which deilne the successively shallower roots conform to the taper of the interior surface of the pipe-end; that the roots of the threads defining the said successively threaded portion toward the outer end thereof,

and if the crests of the threads increase in depth from the outer end. Applicants construction gives a maximum wall thickness. By

making the roots deepest at the smallend of the interiorly threaded pipe-end, a considerable saving in reduction of wall-thickness is effected.

The pipe 10 carries a shoulder 25 for engagement with the end wall of the pipe-end 13 when die Joint is fully screwed up tightly...

clearances 22'between the opposing sides of the the turns make with the axis. of the pipe are not equal ,as they are in Fig. 1. "I'he angles which the left hand sides of the turns of the thread is' and the right hand sides of the thread 19' make with the said axis, vare steeper than the angles which the opposing sides of these turns make vwith the axis. This arrangement provides turns with the less steep angles. In Fig. 3,- the pipes are markedlO'A and 1v1' while the pipe ends are marked 12' and. 13 respectively.

'Referring now toFigs. 4 and 5, the pipes 10" and 11" have their respective ends 12'? and 13" provided with duplex threads separated by annular sealing surfaces 23 and 24 on the respective pipe-ends. Thetwo threads on the pipeend 12", are 18" and onthe pipe-end 13" are 19". Each thread is constructed according to the principles applied to the threads in Figs. 1, 2, and 3. Fig. 5 shows the pipe-end in stabbing relation ready to be screwed together in the usual manner. When the joint has been fully tightened the annular sealing surfaces 23 and 24 100 will be drawn tightly together as shown in Fig. 4; Preferably these surfaces are slightly taperedto increase the tightness of the sealing, but the fit between these surfaces, as also between the corresponding sealing surfaces on Figs. 1, 2, and 3, may be made so tight that in some instances the tapers may'not be required.

We claimz- 1. In a pipe joint, a pipe-end having its interior surface tapered inwardly and threaded, theroots of fthe thread from an intermediate portion of the threaded length to they extremity of the pipe-end becoming successivelyv shallower, and the crests of each succeeding turn of thel thread from an intermediate portion of the threaded length to the extreme inner end -of the thread being cut down toward-the root, thereby decreasing successively the thread depth.

2. In a pipe joint, a pipe-end having its interior surface tapered inwardly and threaded, the roots of the thread from an intermediate portion oi the threaded length to theextremity of the pipe-end becoming successively shallower, and the crestsof the thread from an intermedi- 125 ate portion of the threaded length to the extreme inner end of the thread becoming successively shorter, the crests of the threads defining the said successively shallower roots conforming to the taper of the said interior surface.

3. In a pipe joint, a pipe-end having its interior surface tapered inwardly and threaded,

the roots of the thread from an intermediate portion of the threaded length to the extremity of the pipe-end becoming successively shallower, 13a and the crests of the thread from an intermediate portion of the threaded length to the extreme inner end of the thread becoming successively shorter, the crests of the threads delining the said successively shallower roots con- 14.0 forming to the taper of the said interior surface and the roots of the thread defining the said successively shorter crests conforming also to the said taper. f"

4. In a pipe joint, a pipe-end having its interior surface tapered inwardly and threaded, the roots of the thread from an intermediate portion of the threaded length to the extremity of the pipe-end becoming successively shallower, and the crestsvof the thread from an mtermedi- Leonesa portion of the threaded length to the extremity of the pipe-end becoming successively shallower, and the crests of each succeeding turn of the thread from an intermediate portion o! the threaded length to the extreme inner end of the thread being cut down toward the root, thereby decreasing successively the thread depth, in combination with a pipe-end provided with an exterior thread having complementary engagement with the thread in the first pipe-end. GEORGE M. EATON. HOWARD J. BURNISH. 

